Transcript for Americans Who Stopped Attack on French Train Share Their Story

heroes that helped stop an attack on a train in France. There they are at the far end. Accompanied by America's ambassador to France, taking us inside their decision to stop what they feared could have been a massacre. And we're learning new details about the suspected terrorist. A 25-year-old Moroccan national, already on watch lists. We begin with David Wright in Paris. Reporter: Caught on camera, the immediate aftermath of this foiled attack on a train bound for Paris. He seemed like he was ready to fight to the end, so, so were we. Reporter: The gunman trussed up on the floor. Hog-tied with the conductor's red necktie. Beside him, his small arsenal of weapons. The American that helped him, wounded, but giving first aid to another passenger that had been shot. Now speaking for the first time. I was going to use my shirt, but I realized it wouldn't have worked. So, I stuck two of my fingers into the hole, found what I thought to be the artery and the bleeding stopped. Reporter: Authorities say the quick action of all three Americans saved lives. T the gunman came out of a bathroom, shooting. We saw him with the ak-47, so at that time, it was do something or die. He had a lot of ammo. His intentions were clear. Alex hit me on the shoulder, said let's go. Ran down. Tackled him. We hit the ground. He grabbed the gun out of his hand. While I put him in a choke hold. Seemed like he just kept pulling more weapons left and right. Pulled out a handgun, a box cutter, started jabbing at me with that. Reporter: French authorities identified the attacker as ayub el-khazzani. Born in Morocco. Authorities say he was armed with an ak-47, a pistol, a box cutter and eight extra cartridges of ammo. A lawyer says he is a homeless man planning to rob the train. It doesn't take eight magazines to rob a train. Reporter: Plans to thank them

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